Most plants grow in the a horizon. t f

True

Explanation:

Soils horizons consists of several distinct horizontal layers which are as follows –  

O Horizon -  It is the top, organic layer of soil which is made up leaf litter and humus  

A Horizon – Also known as the topsoil. It lies between the O horizon and the E horizon. In this layer the seeds germinate and the root grows easily as it consists of humus (decomposed organic matter) mixed with mineral particles.

E Horizon – It is the layer is beneath the A Horizon and above the B Horizon. It is made up mostly of sand and silt

B Horizon – This layer is beneath the E Horizon and above the C Horizon. It contains clay and mineral. It is also known as  subsoil.  

C Horizon  It is the layer beneath the B Horizon and above the R Horizon. It is also called regolith and consists of slightly broken-up bedrock.  

R Horizon – It consists of unweathered rock (bedrock) layer  

the real answer is b. scintillation counter

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.