Electron flow down the etc leads to: a. the transport of electrons across the inner mitochondrial membrane from inside the matrixb. the intermembrane space a dangerous imbalance of k⁺ ions across the mitochondrial membrane c. the transport of electrons across the inner mitochondrial membrane from the intermembrane space d. the matrix the coupled synthesis of gtp

a. the transport of electrons across the inner mitochondrial membrane from inside the matrix

Explanation:

The Electron Transport Chain is part of the last stage of cellular respiration, and it basically consists in a series of protein complexes that pump electrons that come from the matrix to the inner membrane space of the mitochondria, and this happens across the inner mitochondrial membrane, which is the place where the protein complexes are located.

From the mitochondrial matrix, eletrons flow to the ETC carried by NADH and FADH, these coenzymes "drop off" the carried electrons (H+) into the protein complexes, so they can be pumped to the inner membrane space in order to create an electrochemical gradient that would then lead to ATP synthesis.

Endocytosis is the process of taking material into the cell by means of infoldings, or pockets, of the cell membrane.