On a hot summer day, you notice a line of dark clouds forming. based on this observation, you go back inside and get an umbrella. what scientific skill have you used.

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.

i think its both a and b