According to my interpretation, the multiple choice answers for questions 33-36 should be all B. Here's my reasoning:
33. Current is always the same throughout a series circuit. It is voltage that changes in a series circuit from resistance.
34. Rock layer Q is the below the other rocks so it is probably the oldest when the rocks are drilled.
35. Heat and pressure is unlikely due to lack of sunlight. Mud covering the psilophytes is also unlikely since water was mainly gaseous at the time and mud requires liquid water to form, which also eliminates D. The most likely answer would be volcanoes because there were many volcanoes existing 400 million years ago as the Earth's crust developed. (If you Biology you'll go into detail with this)
36. Earth could not have been much further away from the sun at the time, so A is not likely. Gravity does not influence light since light is an electromagnetic wave and not matter, so D is very unlikely. The sun was obviously younger at the time, but saying it gave out less energy is not likely because the sun is very old and 400 million years was not a very significant amount of time for the sun's age. The sun was and still is a main sequence star (If you do physics, you'll go into detail about this), ever since Earth was born, so it must have emitted close to its maximum energy at the middle of its age. Also, before life on earth began, (you'll go into detail about this if you do Biology) there was plenty of deadly UV rays bombarding the Earth, the sun must have been emitting plenty of light and UV energy into Earth at the time. This answer may be correct to a small extent, but is not the best explanation.
The "best explanation" for the lack of sunlight (meaning it may not necessarily be the case but is most likely to be) would be there was more dust in the atmosphere. Volcanoes were abundant on Earth at the time, so dust must have been emitted by these volcanoes that were floating in the atmosphere. Since there were so many volcanoes, the amount of dust was enough to reduce the sunlight entering the Earth's atmosphere.
