I say b and d because they both indicate about the heart
They do not have a distinct head and thorax but a fused version of the two called a cephalothorax. That's one of the major differences between insects and crustaceans, both being subgroups of arthropods.
The legislation authorized Medicine Chest be carried on every American Flag vessel of more than 150 tons back in the 1700's, so long as it had a crew of ten or more. A loose network of marine hospitals, primarily in port cities, was established by Congress to care for disabled and sick American merchant seamen around 1798. Federal entities, namely, the Marine Hospital Service, the Public Health and Marine Hospital Service, and lastly the Public Health Service continued to give healthcare to merchant seamen until 1981. The Medical Aid at Sea and Ship's Medicine Chest has been a part of much of this maritime history.
R R Rr is the result of 1st punnet square and the genotype used to produce f2
r
r
