Which is an organ?
a.) heart
b.) circulatory system
c.) blood
d.) muscle tissue

A) Heart

Explanation:

You know dâmΠ well blood is not an organ, it's a body liquid composed of blood cells suspended in blood plasma.

Muscle tissue is what makes a muscle. Note that tissue makes organs : )

Circulatory system:The system that moves blood throughout the body which is composed of the heart, arteries, capillaries, and veins.

That's it, hope this helps you ♡ ;)

A.) heart

Explanation:

Your heart is actually a muscular organ. An organ is a group of tissues that work together to perform a specific function. In the case of your heart, this function is pumping blood throughout your body. Additionally, the heart is largely made up of a type of muscle tissue called cardiac muscle.

did you mean: energy is defined ashyperactivitya caloric measurementthe ability to move matterthe ability to think and analyze this form of energy is called "energy in motion" or "energy of moving matter"potential energy kinetic energy electrical energy1 ptlights on a stage can be examples of all of the following forms of energy exceptelectrical energylight energythermal energysound energywhen one type of energy changes to another this is called energy energy is stored based on their position or shape this is called energy.kinetic potential sound electromagnetic

answer: - few nutrients

high pressure

low temperatures

explanation: 1. few nutrients:   open-ocean zone is located way far from the land, which is the main source of the essential nutrients.2. high pressure: pressure increases by 1 atmosphere for every 10 meters increase in depth.3. ample sunlight: a large fraction of the sunlight is reflected back to the atmosphere from the sea surface. 4. varying salinity: below the thermocline, the water is isolated from the atmosphere so the salinity remains stable over the year.5. low temperatures:   the temperature of open-ocean zone ranges from a low of -2°c to an average of 17°c