When 5-hydroxypentanal is treated with methanol in the presence of an acid catalyst, 2-methoxytetrahydropyran is formed. draw the structure of the second intermediate in this reaction?

The conversion of 5-Hydroxypentanal to 2-methoxytetrahydropyran takes place in two steps. In first step the carbonyl group of 5-hydroxypentanal gets protonated and is being attacked by the hydroxyl group of its own molecule and results in the formation of six membered hetrocyclic ring called tetrahydro-2H-pyran-2-ol. 
The tetrahydro-2H-pyran-2-ol on protonation looses the water molecule results in the formation of second intermediate called as 2,3,4,5-tetrahydropyrylium (Shown in red). This intermediate when attacked by Methanol molecule results in the formation of 2-methoxytetrahydropyran as shown below.

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later

There is no reason to think the results are biased or not conducted properly but you should not assume the results are correct just because they were done in a laboratory so the answer would be c. it is likely to be reliable because the results support the conclusion presented.