Acetylcholine receptors and acetylcholinesterase are membrane proteins that can be found on the cell of a synapse.

Explanation:

Acetylcholine receptor is a kind of integral membrane protein that has a very important role in the binding of neurotransmitters such as acetylcholine and some other. Generally, these receptors are present on the postsynaptic cells to receive acetylcholine neurotransmitter to initiate the signal in the neurons cells and some other.  

     Acetylcholinesterase is a kind of important enzyme that has many important functions in the dissociation of acetylcholine and some other that function as neurotransmitters. This enzyme is also present in the postsynaptic cells.  

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.