Which immune system cells act as hungry scavengers that trap and ingest worn-out cells?

The answer is macrophages. This is a large cell that has the capability of engulfing targeted cells that are infected or damaged. It is a developed monocyte that came from the bloodstream. It has a system of alerting white blood cells and also can be remembered by the immune system once it has been encountered again.

source: https://www.news-medical.net/life-sciences/What-is-a-Macrophage.aspx

Six amino acids have side chains that are polar but not charged. these are serine (ser), threonine (thr), cysteine (cys), asparagine (asn), glutamine (gln), and tyrosine (tyr). these amino acids are usually found at the surface of proteins, as discussed in the proteins 2 module.

The correct answer is c